Adjustable joint trowel



J. W. TUCKER ADJUSTABLE JOINT TROWEL July 28, 1959 2 Sheets-Sheet 1Filed April 26, 1956 &

INVENTOR Jo W Tucker ATTORNEYS July 28, 1959 J. w. TUCKER ADJUSTABLEJOINT TROWE'L 2 Sheets-Sheet 2 7 Filed April 26, 1956 1N\;ENTOR J0 WTucker ATTORNEYS United States Patent 2,896,441 ADJUSTABIJE JOINT TROWELIn W. Tucker, El Paso, Tex.

Application April 26, 1956, Serial No. 580,889

3 Claims. (Cl. 72-136) This invention relates to new and usefulimprovements in joint trowels.

The invention is particularly concerned with trow'els for the bedding oftape in the joints of gypsum wall board, as used in buildingconstruction, and for the filling of such joints to present a smooth andapparently continuous finished surface. At the present time, numeroustypes of trowels are used for this purpose, but they are eitherdiflicult to use properly, or fail to finish the joint in such a mannerthat the joint becomes substantially invisible after decorativecoatings, such as paint, are applied to the wall surface. These trowelsmay have varying degrees of flexibility, and may have a degree oflateral flexibility so as to provide for feather edges on the lateralportions of the bedding or filling cement. In most instances, however,the feather edging which is achieved is not smooth and continuous incurvature or cross-section since the trowels tend to flex at a givenpoint or within a relatively small zone so that the resultant jointpresents a plurality of relatively flat surfaces connected by arcuatesurfaces.

In finishing a joint of this type, it is desirable that the layer ofcement be thickest in the area immediately overlying the joint betweenthe adjacent wall boards, and taper smoothly, with some slightconvexity, outward to lateral feather edges spaced on either side of thejoint. To achieve this result, and to cope with the various types ofjoints and jointing of materials which are encountered, it is desirablethat the trowel flex fairly uniformly in a lateral direction in use, andthat the degree of flexing, or the radius of curvature of the trowelblade edge in use, be subject to variation or adjustment as foundnecessary or desirable.

It is, therefore, one object of this invention to provide an improvedjoint trowel having a flexible blade adapted to yield or bend to providea working edge of the de sired curvature for producing feather-edgedfilling overlying the joints of Wall boards or wall panels.

It is a further object of the invention to provide an improved trowel,of the character described, in which provision is made for regulating oradjusting the degree of flexing or curvature of the woking edge of thetrowel blade, and in which the trowel blade is readily replaceable whendam-aged or worn, or replaceable by a blade of greater or lesserflexibility.

Another object of the invention is to provide an improved joint trowelhaving a working blade adapted to undergo flexing whenapplied to thework surface, but to flex to a greater extent at a central portion andto progressively lesser extents toward its end portions to provide aworking edge of smooth and uniform curvature, and in which the degree offlexing at the end portions of the working blade may be adjusted orregulated in order to vary the curvature of said working edge, and thusvary the contour of the joint produced through use of the trowel.

A construction designed to carry out the invention will be hereinafterdescribed, together with other features of the invention.

The invention will be more readily understood from a reading of thefollowing specification and by reference to the accompanying drawings,wherein an example of the invention is shown, and wherein:

Fig. 1 is a top plan view of a joint trowel constructed in accordancewith this invention,

Fig. 2 is a front elevational view of the trowel,

Fig. 3 is an end elevational view of the trowel,

Fig.4 is a transverse, vertical, cross-sectional view, taken on the line4-4 of Fig. 2,

Fig. 5 is a. view in perspective of the trowel illustrating theapplication of cement to a wall joint and the curvature of the workingedge of the blade when adjusted to minimum curvature, and

Fig. 6 is a view, similar to Fig. 5, showing the trowel adjusted formaximum curvature of the working edge of the blade.

In the drawings, the. numeral 10 designates an elongate, transverseframe member of inverted U-shaped cross-section and having a depending.rearward leg or flange 11 joined to a front leg or flange 12 by atransverse upper web 13 (Fig. 4). A suitable handle 14, formed of woodor any other suitable material, is notched to receive the upper edge ofthe frame member 10 and is joined thereto by a screw 15, shown in brokenlines (Fig. 3). For ease of use, the handle 14 desirably extendsrearwardly and slightly upwardly from the frame 10, but may bepositioned in any desirable or suitable relationship with respect tosaid frame.

An elongate, rectangular, trowelling bladej16, formed of spring steel orsome other suitable flexible or springlike material, is coextensive withthe frame 10 and carries at its rearward edge an upstanding flange 17joined to the blade through a smoothly curving transverse section 18,and desirably being formed integrally or of one piece with said blade.The upper edge of the flange 17 is received within the groove of thechannel-like frame member 10 and abuts the rearward flange 11 thereof(Fig. 4). An angular bracket 19 is provided near each end of the frame10 and has a vertical leg 20 extending upwardly into the channel member.10 and overlying the flange 17, and a forwardly-extending leg 21overlying and spaced above the blade 16. Bolts 22 extend through theflanges 11 and 17 and the vertical legs 20 of the brackets 19, andreceive nuts 23 within the channel-like frame member 10 for securingboth the blade 16 and said brackets thereto.

The forwardly-extending horizontal legs 21 of the brackets 19 extend anysuitable or desirable distance forwardly over the upper surface of theblade 16, it having been found preferable that the legs 21 extend fromonethird to one-half of the dimension of said blade takenperpendicularly to the frame 10.

As shown in Figs. 1 and 4, each of the brackets 19 is provided in itsforwardly extending leg 21 with an elongate slot 24 having itslongitudinal axis disposed perpendicularly to the frame member 10 andextending forwardly over the upper surface of the blade 16. Suitablescrews 25 extend downwardly through the slots 24 and by means of nuts 26clamp to the underside of the forwardly-extending legs 21 angular stopor pressure elements 27 having rearwardly-extending legs 28 underlyingand clamped to the underside of said legs 21, and short,downwardly-extending feet or lugs 29 which engage the upper surface ofthe blade 16. The feet 29 provide points of support against upwardflexure of the blade 16, these points being positioned near the ends ofsaid blade and being adjustable toward and away from the forward orworking edge 30 of said blade to vary the degree of flexibility of thoseportions of the blade immediately for-.- ward of said feet.

. a l 3 It is pointed out that movement of the screws 25 toward the rearof the slots 24 will move the feet 29 away from the working edge 30 ofthe blade 16 and cause the end portions of said blade forward ofsaid-feet to be more flexible because there is a'greater expanse thereofunsupported by the frame 10 or said feet. Similarly, movement of thescrews 25 toward the front ends of the slots will move the feet 29toward the working edge'of the blade, thus reducing the width of theunsupported end portions of the blade and decreasing the flexibilitythereof. a

The central portionof the blade 16 is supported only by the frame 10 andretains substantially the same degree of flexibility at all times, andhence, as illustrated in Figs. and 6, adjustment of the feet 29 towardand away from the forward or working edge 30 of-the blade 16 will resultinthe blade flexing in use to provide a greater or lesser degree oftransverse curvature and provide a joint of greater or lesser thicknessat its central portion.

- At the same time, the desired, uniform flexibility or curvature of theblade is retained to the extent that the blade will flex smoothly and toprogressively lesser degrees from its central portion to its endportions, and accordingly, a smoothly curved joint with feather edgeswill be obtained. Such a joint is highly desirable in that it issubstantially-invisible when covered by decorative coatings.

There is no flexing of the blade at localized spots, resulting in ajoint that remains visible after covering or painting, but instead, asmoothly and uniformly curved surface for the joint cement is achieved.At the same time, the radius of curvature or degree of curvature of thejoint surface may be regulated or varied at will by suitable adjustmentof the elements 27.

Of course, by tilting the trowel with respect to the work surface, theeffective surface curvature of the layer of joint cement may be variedwithout adjustment of the elements 27. Most workmen, however, have anadopted style of use of such trowels, and the provision for adjustingthe transverse curvature of the blade 16 is most advantageous in copingwith the different joint materials and the different types of jointsencountered in building construction. Further, the adjustability of theblade permits the workman to adapt the blade to his particular style ofoperation whereby better work may be accomplished with less lost motionand waste of time.

Of course, the blade 16 is readily detached from the frame by removal ofthe bolts 22, and may be replaced by a new blade, or by a blade ofgreater or lesser flexibility or of differing dimensions. The structureis extremely simple and economical to manufacture, and yet is durableand is convenient to use. Proper adjustment of the elements 27 will fitthe tool to the working habits of the particular workman, or will enablethe workman to adapt the tool to various joint forming problems.'

A typical wall board joint is shown in Figs. 5 and 6, and includesa pairof abutting wall board panels 31 having their joint or abutting edgescovered by a tape 32 over which the bedding and filling material orcement 33 is placed. It is desirable that the central portion of thelayer of filling material, immediately overlying the tape 32, be ofrelatively greater thickness at the central portion 34 than the lateralportions 35, and that the latter feather edge smoothly into the surfaceof the 4 v v panels 31. It is also desirable that the curved outersurface of the layer of filling material or cement be smoothly curvedand present no planar surfaces or sharply curved surfaces, but flow in asmooth continuous, and substantially uniform, curve from one featheredge to the other. By longitudinal movement of the trowel describedherein lengthwise, of the joint, the filling cement is applied theretoin the desired manner, as illustrated in Figs. 5 and 6, and at the sametime excess quantities of said cement are prevented from flowingoutwardly over the edges or end portions of the blade 16. By rearward orforward adjustment of the elements 27, the transverse curvature of theforward or working edge 30 of the blade 16 may be decreased (Fig. 5) orincreased (Fig. 6) and the thickness of the central portion 34 of thejoint filling material correspondingly decreased or increased.

The foregoing description of the invention is explanatory thereof andvarious changes in the size, shape and materials, as well as in the.details of the illustrated construction may be made, within the scope.of the appended claims, without departing from the spirit of theinvention.

What I claim and desire to secure by Letters Patent is:

1. An adjustable joint trowel including a rectangular flexible bladehaving a working edge on one of its longitudinal margins, the bladebeing relatively wide and of greater length than width, a substantiallycoextensive frame member attached to the opposite longitudinal margin ofsaid blade, a bracket attached to each end portion of the frame memberand extending laterally therefrom in overlying spaced relation to saidblade,the lateral projection of the brackets being not greater thanonehalf the width of said blade, support elements extending transverselyof said blade in overlying engagement with its end portions andterminating between its longitudinal margins for preventing upwardflexure of the end portions of the working edge while permitting upwardflexure of the intermediate portion of said edge, and means foradjustably fastening the support elements to said brackets fortransverse movement between the longitudinal margins of said blade tovary the curvature of said working edge when said blade is flexed.

2. An adjustable trowel as set forth in claim 1 wherein the supportelements are spaced from the blade and have feet depending from theirouter ends for engagement with said blade.

3. An adjustable trowel as set forth in claim 1 including an upstandingcoextensive flange on the longitudinal margin of the blade opposite itsworking edge, the brackets being angular and having upright legsoverlying the flange and substantially horizontal legs to which thesupport elements are adjustably fastened, and common means forconnecting the upright legs and flange to the end portions of the framemember.

References Cited in the file of this patent UNITED STATES PATENTS1,297,541 Campbell Mar. 18, 1919 1,744,097 Baker et a1. Jan. 21, 19302,301,498 Ames Nov. 10, 1942 2,519,946 Voelker et a1. Aug. 22, 19502,725,740 Borgstrom Dec. 6, 1955 2,800,672 Gilyan July 30, 1957

